This invention is related to shaft turning mechanisms and, more particularly, to a mechanism for converting bilateral oscillation to unilateral oscillation.
In some applications such as, for example, interconnection of potentiometer and switch shafts it is advantageous to provide rotation of the potentiometer shaft in one direction regardless of the direction of rotation of the switch shaft. In an electric vehicle control there is normally provided a rotatable switch having a shaft which rotates in one direction for forward motion of the vehicle and rotates in a second direction for reverse motion of the vehicle. The switch shaft is generally connected to the shaft of a speed control potentiometer. The amount of angular displacement of the potentiometer shaft determines speed or torque of the vehicle and the direction of displacement establishes the direction of travel of the vehicle. In the past it has been necessary to provide a potentiometer which is balanced against a center position such that equal angular rotation of the potentiometer shaft in either a forward or reverse direction produced equal proportions of resistance change since the potentiometer shaft followed the switch shaft. This further required an elaborate alignment procedure to initially set the potentiometer in the correct position and further required frequent realignment of the potentiometer.
Accordingly it is an object of the present invention to provide a mechanism for effecting unilateral rotation of one shaft in response to bilateral rotation of a second shaft.
In accordance with a preferred embodiment there is provided a substantially u-shaped linkage member mounted at a bight thereof to a first bilaterally oscillatable shaft, and a second elongated linkage arm mounted to a second shaft. The second arm is adjusted to lie at an angle between the legs of the u-shaped member whereby upon rotation of the first shaft in a first direction, one leg of the u-shaped member will engage a first end of the second arm to cause rotation of the second shaft in a first direction. Upon rotation of the first shaft in a second direction, the other leg of the u-shaped member will engage an opposite side of the second arm again causing rotation of the second shaft in the first direction.